Block-signal system for electric railways.



P. W. SAWYER. BLOCK SIGNAL SYSTEM FOR ELECTRIC RAIL-WAYS.

APPLICATION FILED JULY 20, 1903.

Patented Feb. 9, 1915.

1 10 KIM 17 40 WMM/b THE NORRIS PETERS C0. PHOTO-LITHO WASHING roN. D

, ing-units, which may take various forms,

s'raias rare FRED SAW'YER, 0F BOSTON, MASSACHUSETTS, ASSIGNOIR, TO THE UNION SWITCH" A ND SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A. CORPORATION OF PENNSYLVANIA.

BLooK-sIeN LsYsrEM FOR ELECTRIC RA1IL-WAYS..

mas er.

, To all whom it'mag concern-.-

I enable both car-rails to be employed for the" return of the car-operating current supphed by the trolley-wire or power-rail and to allow the two rail-lines to be cross-bonded if desired so as to maintain alike potential in each rail. 7

In the preferred form; herein-illustrated, for. carrying the invention into eiiect, the two rail-lines are each composed of sections forming blocks and the several "sections of each rail or rail-line are bonded together by impedances which afford a free passage to the direct car-operating current but impose I a reactance or inductance in the path of the alternating current or currents employed to control the block-signals. Suitable signalare associated with the several signalingblocks and supplied with alternating curby the passage of. a car into the block and acting through suitable connections to con-' trol the signal and set it inlthe danger-position. Other impedances are; or may be employed to cross-bond the rail-sections of each block and maintain the two rails at an even trio-railway signaling system embodying this invention. Fig. 2 represents a VIQW showing a modification of the system. Fig. 3 represents a power-operated element for Substitution. in said modification.

Specification of Letters Patent.

1 units.

Patented Feb. 9; 1915.

Application filed July 20, 1903. Serial No. 166,214.

The same-reference characters indicate the same parts in all the figures.

Referring to Fig. 1, 10 10 indicates the two rails or rail-lines forming the car-track, and each rail divided into sections whose pairs form a series of signaling-blocks 12 13 1-1. At the joints between adjacent blocks, the rail-ends may be separated by insulation 15' but the sections are not electrically isolated as will appear. The pair of wheels'and axle 16 symbolize a car running on the rails and adapted to effect an electrical connection between them.

17 '17 are impedances bonding the adja-- cent sections of each rail 10 and so constructed as to be of low ohmic resistance but capable of imposing a'reactance in the path of the alternating. currents supplied to the blocks so as to prevent, the passage from one block to anotherof an alternating current in such a condition-as to eifect. the operation of the signal. Similar impedances 18 are inserted as cross-bonds between the pairs of rail-sections of the several blocks, said impedances being constructed to freely pass the direct current and thus maintain an even potential in the two rails,'but reacting against the passage of an alternating ,cur-

rent capable of operating the signaling- 19 represents the trolley-wire or r1Rowerrail for supplyingdirect current to t e cars, and 20 represents the direct-current generator-set connected to said wire or rail and to the track-rails 10 10.

nected in circuit between the'wire 19 and rails 10, and an alternating-current generator 23 having its shaft coupled to that .of the motor. The circuit-wires 24 25 of this alternator are connected to the respective rail-sections 26 2'6-of the block 13 and in the circuit of the generator is interposed a protective element 27 which may be either an' impedance or a resistance. -.A rotary converter is of. course a well-known substitute for the motor-generator'and is an equivalent in this connection;' 'Both ofthese olevices and their equivalentsl include under the term mechanical power-operated device, meaning a device having movable mechanism influenced by the variation in power-function of the alternating signalblock current and influencing the direct current which controls the signal. The circuit of the motor 22 contains a relay 28 controlling a local circuit 29 for operating the signal-device 30.

In the operation of the above-described device, it is evident that when the car 16 is in the block 12- or any block antecedent to the block 13, the alternating-current supplied by the continuously-propelled alternator 23 will find a complete circuit through the alternator, the car-rails l0 and the car 16, but will have its power-function altered by having to pass through one or more pairs of impedances 17'. The alternating current passed by these impedances and also by the impedance 18 in that block is a lagging and largely a wattless or non-power-consuming current and therefore the effort required of the motor 22 to drive the alternator 23 is relatively small. Hence the circuit of the motor 22 will not pass enough current to operate the relay 28 and close the circuit of the signal 30. After the car 16 has passed the impedances 17 and entered the block 13, it short-circuits the impedance l8 and directly completes the circuit of the alternator 23. The current supplied by said alternator will then be'in phase or nearly so, and hence More effort is a power-consuming current. required of the motor 22 to drive the alternator 23 and more current passes through the circuit of said motor and through the relay 28. Said relay will be operated by this increase of current and'will set the si nal 30 in the danger-position. As soon as the car passes out of the block 13 into the block 14 the impedances 17 connecting said blocks 13 14 become interposed between the car and the block 13 and the signal 30 resumes its safety-position.

In the modification shown in Fig. 2, an alternator 31 common to the several blocks, supplies through transformers 32, alternatingcurrentto thealternatingcircuits33 of the several blocks,there being,as will be well understood, a transformer for every block. In the circuit 33 is interposed a solenoid 3a for operating the signal 30 and which may, as shown, be shunted by condensance 35 to counteract the current-lag imposed by the solenoid. Said solenoid is a current-operated device as distinguished from a poweroperated device, that is, its operation depends upon variations in the current flowing in the circuit 33 (and not upon variations in the power supplied by said circuit). Such an installation would require a more expensive construction of the impedances 17, which I have shown connecting the rail sections of adjacent blocks in this view, and

for this reason the formof the invention shown in Fig. 1 is preferred, although I regard Fig. 2 as a practicable construction.

It will be apparent that instead of the current-consuming solenoid 3% in Fig. .3, I may substitute any suitable power-operated device for controlling the signal 30, such for example as the device shown in Fig. 3, in which a field 36 varies the torque on a spring-held armature 37 controlling a local circuit 38. In such a case the expensive construction of the impedances 17 above alluded to is avoided.

Referring to I ig. 3, 40 is a resistance in series with the winding 39 of the magnet 36 and acting to restrict the delay'of phase of current through the coil 39. 11 is a winding on stationary core 42, said winding being connected in parallel with the branch including coil 39 and resistance 40. As shown, the fields due to these two windings are at right angles to one another and differ in time as indicated. The spring-held armature 37 is any suitable induced element, such as a cylinder of copper or aluminum. 4-3 18 a contact arm arranged on the armature 37 which is rotated against the tension of the spring 45 to make contact with the terminals 4:4: of the local circuits 38. This induction relay device consumes a comparatively small quantity of energy, thus avoidmg an expensive construction of the impedance 17, as stated.

It will occur to those conversant with the art that the principles of this invention extend to electric-traction systems employing two conduit-wires or two over-head wires, one of which acts as a return for the other, in which case the arms of the shoe or double trolley would be connected by a device such as a condenser for passing the alternating current but not the direct current. As I do not, however, consider this application of the invention a particularly useful one in the present state of the art, I have not made special illustration of it.

I claim 1. The combination with a railway system comprising traffic rails and an electric power circuit of which the rails form one side; ('5 signal block circuits formed by insulations at intervals in each rail; a source of alternating current for each signal block circuit; impedances shunting the insulations in said rails and acting to ive electrical continuity to both rails as conductors for the power current while restricting the difference of potential due to the sources of signal current to their respective blocks, and im pedances connected as cross-bonds, equalizmg dificrences of potential due to power circuit but maintaining differences of potential due to the sources of signal current.

2. The combination with a. railway system comprising traliic rails and an electric power circuit of which the rails form one means? side; means for dividing the rails into sections so that they may form part of track circuits; a source of alternating current for each track circuit; a signal circuit for each track circuit; and means for controlling said signal circuits by chan es in power factor of the current furnished to its track circuits. V 4

3. The combination with a railway system comprising trafiic rails and an electric power circuit of which therails form one side; means for dividing the rails into sections so that they may form parts of track circuits; a source of alternating current for each track circuit; a signal circuit for each track circuit; a relay device controlling said signal circuit and connected across the power ci'r-' cuit; and means whereby said relay is responsive to variations of a characteristic of the track circuit current.

4. The combination with a railwa system comprising traflic rails and an e ectric power circuit of which the rails form one side; block sections formed by rail insulations; impedances shunting said insulations; a signal circuit for each block section; signal circuit controllin means located in a primary circuit; an a source of track circuit current secondary with respect to said primary circuit.

5. In a signal system; signals; signal circuits for said signals; a source of alternating current corresponding to each signal and connected between the track rails corresponding to said signal; and means controlling said .signal circuits in response to changes in the power factor of the alternating currents in the track rails.

6. In a signal system; block signals guarding successive portions of track; signal circuits for said signals; a source of alternating current'connected between the rails of the portion of track guarded by each signal; and a relay device for each source including a rotor and a stator having a plurality of v by the current energizing coils carrying currents ofdierent phase, each rela device controlling the corresponding signa circuit. 7 v

In asignal system; trafiic rails divided by insulation to form block sections; a

source of alternating current for each such section connected between the rails thereofa si a1 circuit for each block section; and an induction motor rela device having a rotor and a plurality o stator energizing circuits controlling each signal circuit.

9. A relay for alternating currentsignal I system comprising an armature acting in.

response to magnetizing impulses displaced in phase and in position; a stationary field magnetsystem producing said impulses and energized by a plurality of energizing coils; and means for producing currents of difierent phase in said coils.

10. In a signal system; block signals guarding successive portions of the track; signal circuits for said signals; a source of alternating current connected between the rails of the track arded by each signal; and a'relay device or each source including a rotor, a stator, and a plurality of-energizing coils carrying currents of difierent responding signal circuit.

In testimony whereof I have afixed my signature, in presence of two witnesses.

- FRED'W'. SAWYER. Witnesses:

R. M. PIERsoN, A. C. Barman.

I phase, each relay device controlling the 'cor- 

